The present invention relates to a method for forming relatively narrow thin film lines. More particularly, the invention relates to a method for forming such lines on a semiconductor substrate.
In the fabrication of semiconductor devices, it is frequently desired to generate features having small physical dimensions. For example, narrow conductor lines having widths on the order of several microns are frequently utilized to interconnect various portions of a monolithic integrated circuit. The use of narrow interconnection lines allows larger areas of the integrated circuit to be devoted to actual devices, thereby achieving greater packing density. As a second example, relatively narrow lines are an objective when fabricating the gates of high frequency field effect transistors (FETs). Since FET frequency response relates to the inverse of channel length, and a narrow gate creates a narrow channel region, higher frequency switching can be achieved if narrow gate lines are used.
Lines having widths less than 1 micron can be fabricated using present semiconductor processing technology. However, elaborate, sophisticated and expensive photolithographic equipment and techniques must be resorted to. Electron beam or X-ray exposure systems are usually employed and other processing constraints are frequently created as well. Described herein is an invention which permits the fabrication of submicron width lines using relatively simple processing techniques.